A classic in its native Scandinavia, Axel has a cool rock 'n' roll flavor in the US, thanks to Guns N' Roses' Axl Rose (born William). With its distinctive letter 'x', it has an effortlessly cool vibe about it, and is currently growing in popularity.

Now that it's no longer fashionable for girls, Robin is rising for boys again. Robin Hood, Robin Williams, Christopher Robin, and Robin the Boy Wonder are all male namesakes, after all. It reentered the US Top 1000 boys names in 2015 for the first time since 1999 and continues to bounce around the lower end of the Top 1000.

The luminous Ingrid Bergman's appeal was strong enough to lend universal charisma to this classic Scandinavian name, which has been somewhat neglected in the US. Even today, a child named Ingrid would be assumed to be of Scandinavian ancestry, signaling the name has never been fully integrated into the English lexicon the way other European choices from the same era like Danielle or Kathleen have.

Chosen for their daughter by Bruce and Demi (inspired by the To Kill a Mockingbirdcharacter), and for her son by Tai Babilonia, an interesting choice for either sex, with overtones of a "good scout" and the upstanding qualities of a Boy/Girl Scout.

Nova has the feel of both newness, from its meaning, and great energy as an astronomical term for a star that increases suddenly in brightness before fading.

Jackson is one of those names that's much more popular than you think, coming in near the top of our annual Playground Analysis, which ranks names by grouping all their spellings together. Last year, more than 13,000 baby boys were named Jackson -- along Jaxon, Jaxson, Jaxxon, Jaxen, Jaxyn, Jaxsen, and Jaxsyn -- which counted together makes it the Number 5 boys' name.

With mythological names rising, the handsome son of Zeus and god of medicine, music, and poetry among many other things might offer an interesting, and melodic option. Similar in style to Atlas and Atticus and similar in sound to Arlo, Paolo, Paul, and Ollie, Apollo entered the US Top 1000 back in 2012, and was propelled upwards after it was chosen by Gwen Stefani and Gavin Rossdale in 2014.

While Gwen may have originated as a short form of Gwendolen and Gwendolyn, these days it frequently stands on its own. Rocker Gwen Stefani has given it a shot of cool, and parents are choosing it as a standalone more and more often—Gwen hopped back onto the US Top 1000 in 2013 after an absence of over 30 years. Gwen could also be short for Guinevere.

Greta is an Old World name long tied to the iconic Garbo, but now synonymous with environmental activism.

Although this is traditionally seen as a female name, via the classical mythological nymph who pined away for Narcissus until all that remained of her was a disembodied voice — it can also be used for boys. Remember that old song, 'Little sir echo, how do you do?'

Holly ranks just in British Top 50, but it's been out of favor here since the 1970s Era of Nickname Names. Still, the name may be on her way back as a rejuvenated nature pick.

With its cool -X ending, Jax is an update on the classic nickname Jack, likely inspired by the rise of Jackson. It garnered attention in the US thanks to the game, Mortal Kombat II back in the '90s, and was pushed up the charts when it was used in the show Sons of Anarchy, in which Jackson "Jax" Teller is the central character.

Leif is one of the most recognizable Scandinavian names, thanks to Icelandic explorer Leif Erikson, and is still one of the best, with a pleasant aural association with the word leaf.

A name of multiple identities: a somewhat soap-operatic single-syllable surname, a homonym for the biblical bad boy Cain, and, when found in Japan and Hawaii, it transforms into the two syllable KA-neh. Kane also has multiple meanings: in Welsh, it's "beautiful"; in Japanese, "golden"; and in Hawaiian, "man of the Eastern sky."

A popular choice back in the 50s and 70s, Rocky fell into decline after Sylvester Stallone's battered but not beaten boxer character became the overwhelming association many had with the name. Now, nearly five decades on from when the first Rocky movie was released, this tough yet playful name is back in style, ready to forge an identity of its own. Given to around 420 boys in the US in a recent year, it was one of the fastest rising names in the charts.

This Welsh nature name that can be pronounced exactly like the male Ira. Or, to avoid confusion, you could just name her Snow.

Lost in limbo for decades and decades, Elsa now stands a good chance of following along in the progression from Emma to Ella to Etta, thanks to the ice queen heroine who "Let It Go" in the wildly popular Disney movie Frozen. The name shot all the up to Number 286 (its highest ranking since the 1890s) in the year after the release of the movie, though it's now dropped back down the list in the US.

Introduced to the American public by actress Neve Campbell; it was her Dutch-born mother's maiden name. Neve is an interesting and fresh new possibility, one which Conan O'Brien chose for his daughter.

Lumi may be a rare girls' name in the USA and England, but it comes in the Top 50 in Finland, where it means snow. Given the popularity of Winter, Holly, Ivy and many other wintery-christmassy names, we think that short and spunky Lumi definitely has potential for greater usage outside its home country as one of the more unusual names for Christmas babies.

The e-addition takes the name from slightly hippie-ish nature name to the place name of a picturesque island off the coast of Scotland, and for baby namers it's by far the more popular spelling.